The ion source has been widely applied in aspects such as injection into solid surfaces, micro-machining, material surface modification and neutral beam injection, and has become an indispensable apparatus in many basic research fields, for example, studies of atomic physics, plasma chemistry, nuclear physics, material modification, etc. Ion beams extracted from the ion source have become an indispensable machining process and manufacturing approach in fields such as high-energy physics, microelectronics, photoelectronics, metallurgy, aerospace, medical instruments, mechanical manufacturing and heating for nuclear fusion.
For a conventional ion source generation apparatus, during the extraction from a pure positive ion source or a pure negative ion source, backstreaming of charged particles occurs. The backstreaming of the charged particles will result in sputtering or overheating of the backplane opposite to the extraction gate in the plasma generation region. For example, when a negative DC voltage is applied to the positive ion source extraction gate, the positive ions are extracted while the electrons and negative ions are repelled; and the electrons and negative ions are accelerated to high energy where they pass through the plasma generation region and hit onto the backplane to result in overheating and sputtering of the backplane. Similarly, when a positive DC voltage is applied to the negative ion source extraction gate, the negative ions and electrons are extracted while positive ions are repelled; and the positive ions are accelerated to high energy where they pass through the plasma generation region and hit onto the backplane to result in sputtering and overheating of the backplane. The backplane suffering from long-term sputtering and overheating will have greatly decreased service life, and particles sputtered from the backplane will contaminate the plasma or even the ion source.